This invention relates to a mixer with a new outlet valve and in particular, to a container with a poppet valve located at the bottom outlet, which valve may be lowered for closing the outlet and raised for emptying the container, permitting mixing of successive batches of material with grinding media without requiring external separation of the grinding media.
Mixers have been used for making various materials such as paint, plastics, inks and powders. A grinding media such as glass beads, metal shot, pebbles, and the like, is used with the material being mixed for the purpose of producing the desired fineness and homogeneity in the resulting mixed material.
Typically such a mixer includes a container with cover and a motor-driven agitator for positioning adjacent the bottom of the container, with the agitator shaft passing upward through the cover. Means may be provided for heating the container and/or introducing steam during the mixing operation, as desired.
One of the principal problems associated with this mixing process is the separation of the grinding media from the fluid material when the mixing is completed. In the prior art containers, a fixed screen is positioned at an outlet opening in the bottom or in the side near the bottom, with the outlet opening closed by an outer cover. The screen is exposed to the batch and media and there is heavy wear on the screen during mixing, requiring frequent replacement of the screen. Accordingly, it is the object of the present invention to provide a new and improved mixer incorporating means for separating the grinding media from the mixed material at the time the material is removed from the mixing container, which separating means is protected during the mixing operation. A further object is to provide such a mixer wherein the separating means, typically a screen, may be moved during emptying of the container to displace media which tends to pack at the screen.